# std::derived_from

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< cpp‎ | concepts

Defined in header `<concepts>` |  |
template< class Derived, class Base > concept derived_from = std::is_base_of_v<Base, Derived> && std::is_convertible_v<const volatile Derived*, const volatile Base*>; |  | (since C++20)

The concept derived_from<Derived, Base> is satisfied if and only if `Base` is a class type that is either `Derived` or a public and unambiguous base of `Derived`, ignoring cv-qualifiers.

Note that this behavior is different to `std::is_base_of` when `Base` is a private or protected base of `Derived`.

### Example

Run this code

    #include <concepts>

    class A {};

    class B : public A {};

    class C : private A {};

    // std::derived_from == true only for public inheritance or exact same class
    static_assert(std::derived_from<B, B> == true);      // same class: true
    static_assert(std::derived_from<int, int> == false); // same primitive type: false
    static_assert(std::derived_from<B, A> == true);      // public inheritance: true
    static_assert(std::derived_from<C, A> == false);     // private inheritance: false

    // std::is_base_of == true also for private inheritance
    static_assert(std::is_base_of_v<B, B> == true);      // same class: true
    static_assert(std::is_base_of_v<int, int> == false); // same primitive type: false
    static_assert(std::is_base_of_v<A, B> == true);      // public inheritance: true
    static_assert(std::is_base_of_v<A, C> == true);      // private inheritance: true

    int main() {}

### References

- C++23 standard (ISO/IEC 14882:2024):

  - 18.4.3 Concept `derived_from` [concept.derived]

- C++20 standard (ISO/IEC 14882:2020):

  - 18.4.3 Concept `derived_from` [concept.derived]

### See also

is_base_of (C++11) | checks if a type is a base of the other type (class template)
is_convertibleis_nothrow_convertible (C++11)(C++20) | checks if a type can be converted to the other type (class template)

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